In a 360-degree audio/video application, a plurality of cameras and microphones are used to record audio and video tracks for use of virtual reality. When a user wears a head-mounted display or a headphone to enjoy the virtual reality, the recorded audio and video tracks can be played by the head-mounted display or the headphone to provide an immersive experience to the user. However, because the audio tracks are recorded by two or more microphones, and starting-time of microphones (i.e. time points that the microphones start to record) are always different due to the internal hardware or software situations, the audio tracks may not be intrinsically synchronized.